Knife sharpener attachment



Feb. 21, 1956 HOLZHAUSEN ET AL 2,735,247

KNIFE SHARPENER ATTACHMENT Filed June 23, 1953 61.5w Hl'afLZA/AUSEAA WILL/AM W .FIZEFL/GEB,

IN V EN TORS.

BY b/"7 United States Patent *KNIFE SHARPENER ATTACHMENT Glen H. Holzhausenand William W. Haefliger, Los Angelles, Calif.

Application June 23, 1953,-Serial N0. 363, 355 6 Claims. (Cl. 51-241) This inventionrelates to devices for sharpening knives .and similar articles and more particularly concerns sharpening devices adapted to be connected to and ro- .tatably driven by the shafts or blades of heaters of the type forming the working components of home electric mixers.

It is an object of the invention to provide a novel sharpening unit which may be readily attached in rotatable driven relation with the shaft of a beater of a home electric mixer.

It is another object of the invention to provide a novel sharpening device which may be readily attached in rotatable driven relation with any shaft having a diameter .lying within a limited range of sizes, and thereby to provide a means for attaching the sharpening unit to various sized beater shafts of the common types found on home electric mixers.

It is another object of the invention to provide-a novel means for connecting a sharpening unit in rotatable ensharpened to the extent that excessive wearing away and heating of the sharpened edge of that object will be prevented.

It is another object of the invention to provide a novel sharpening unit having an annular sharpening groove so as to provide an automatic centering means forthe blade of an object being sharpened, in order that wobble of the sharpening unit during rotation thereof will not adversely alfect sharpening of the blade.

It is a further object of the invention to provide a novel sharpening unit which may be connected in rotatable engagement with the blades of a heater of a home electric mixer.

Further objects and advantages of the invention will be-understood more clearly and fully from the following detailed description with reference to the accompanying drawings in which:

Fig. 1 is a cross sectional view of one form of the present invention;

Fig. 2 is a cross sectional view of the invention taken on line 22 of Fig. 1;

Fig. 3 is a fragmentary cross sectional view of a portion of the sharpening unit illustrated in Fig. 1;

Fig. 4 is a fragmentary cross sectional view of the con nection means for the sharpening unit and illustrating a 2%, when the plugis inserted therein. centrally located cylindrical vaperture 30'forrned therein, "and a longitudinal slot or groove 31 connects itheaper- 2,735,247 Patented Feb. 21, 1956 Fig. 9 is a cross sectional viewtaken on line 9--9 of Fig. 8.

Referring now to Fig. 1, there is.illustrated therein a preferred form of the :sharpening unit 10 which includes an upper abrasive member 11 and alower abrasive member 12, each of which is annular in shape and has a beveled or tapered edge 13 on member 11 and Men member 12, both facing one anotherto form a V -shaped knife sharpening and centering groove 15 therebetween. The abrasive elements are 'mounted'on disc shaped housings 16 and 17 which serve to protect the abrasive ele means and also as centering or aligning means therefor.

Each housing or base member extends alongthe flat side of its corresponding abrasive-element which lies opposite the beveled edge thereof, and centrally located apertures 18 and 19 areformed respectively in the housings 16 'and17 to co-operatively receive a walled connecting member 20. The connecting member 20 has turned over edges or lips 21 and 22 at its upper and lower extremities, respectively, which engage the inner annular portions 23 and 24 of the housings 16 and 17. The inner wall 25 of member 20 is tapered, axially, to co-operatively receive and engage a resilient tapered member such as plug 26, which is made of rubber. Plug 26 forms a means for frictionally coupling the sharpening unit 10.to

a rotatable shaft 27.

The plug .26 may be inserted within the aperture enand the outer side wall 28'of plug 26 is adapted to frictionally engage the innerwall 25 of connection member The. plug has a ture 39 withthe outer side wall 28' of the-plug.

The plug is adapted-to be fitted onto a-shaft 27 which has a diameter equal to or somewhat greater or smaller than thediameter of .the cylindrical aperture 30 of the plug. This may be accomplished by spreading the re silient plug walls 32a and 32b adjacent the'slot 31 so that the shaft 27 may he slipped through expanded slot '31 into the cylindrical aperture 30.

When plug 26 is fitted onto the shaft 27 of an electric mixer beater with its widestend face 29 facing toward the beater blades 34, the sharpener-unit 10 maytbe'slipped over 'the'upper end 35 .of the shaft, over thecollar 36 mounted on the shaft, and onto the taperedplug 26, so as to bring the tapered wall 25 of thesharpene'r unit into engagement with the tapered wall 28 of the plug. The sharpener unit 10 may then be'pressed downwardly onto the plug to compress the plug body 32 radially inwardly. Thebody portions 32a and 32b are correspondingly deflected toward and into the slot 31 in body 32. The tapered wall 28 will then exert outwardly directed forces against the inner tapered wall 25 of the sharpener unit 'equal'and opposite to the inwardly directed forces ofcornsharpening unit 10, so that the two will not separate in the absense of an external force tending to separate'them, axially.

Furthermore, the forces of compression tending to force the resilient plug body 32 inwardly also serve toshrin'k the aperture 31 so that the friction surfaced aperturewall 37 will grip the shaft 27. Thus the plug forms a means for coupling the'shaft 27 in rotatable engagement with the sharpener unit 10, and as a consequence, torque maybe transmitted from shaft 27 to thesharpener .unit .10. .It is also pointed out that the construction ofthe resilient plug is such that the plugtis enabled to slip on the shaft 27 should the forces resistingrotation of thesharpener unit arising from a knife sharpening operation exceed the tangential frictional forces between the shaft and aperture wall 37. Thus excessive wearing away and heating of the blade edge will be prevented when the sharpening load becomes too great.

Additional means for preventing the destruction of the sharpened feather edge of a knife blade during a sharpening operation may also be provided in the sharpener unit. As seen in Fig. 3, a small groove or slot 40 is provided between the proximate surfaces 41 and 42 of the upper and lower abrasive members 11 and 12 respectively, and at the apex of the V-groove 15. Slot 40 is provided either by removing abrasive material between proximate surfaces 41 and 42, or by deflecting the annular portions 23 and 24 of the housings 16 and 17 toward one another so that the abrasive units 11 and 12 and proximate surfaces 41 and 42 will diverge slightly as by pivoting about the circular pivot line 43. The connecting member 29 provides the force necessary to deflect portions 23 and 24 toward one another since the edges or lips 21 and 22 of member 28 are spaced apart a distance less than the spacing of the outer surfaces of housing members 16 and 17 in their undefiected condition. The slot 40 is adapted to receive a knife blade edge during a sharpening operation and the blade edge will seek the slot since the V-groove tends to center the blade between the annular beveled edges 13 and 14. Thus the structure provided enables the blade to be sharpened without destroying the feather edge thereof. Furthermore, the provision of the V-groove 15 and the slot 40 provide a means for minimizing uneven sharpening of the blade should the sharpening unit tend to wobble in rotation, for the groove and slot constantly tend to center the blade edge in the V-groove.

The connection means 44 illustrated in Fig. 4 includes a pair of oppositely disposed spring clips 45, which are elongated in the general direction of the shaft 27, and which have end portions 46 which are bowed inwardly toward the shaft. Frictional gripping means such as the rubber shoes 47 are fastened to the end portions 46 of each clip 45, and each shoe has a curved inner face 48 adapted to engage a portion of the shaft when pressed against it. The pair of clips are joined together by means of another spring clip 49 which is bowed into a U-shape forming two arms 50 and 51 each of which is fastened to a lower end portion 46 of a spring clip. The mid portion 53 of each spring clip 45 is dished or offset inwardly toward the the shaft between upper and lower shoulders 56, and carries'a frictional gripping element such as a rubber sheet or sleeve 54 which is bonded thereto and faces outwardly therefrom.

When it is desired to mount the sharpening unit 55 and the connection means 44 on the shaft 27, the legs 50 and 51 of the spring clip 49 are spread so that the shoes 46 on clips 45 may slip over the shaft diameter, permitting the curved inner faces 48 of the shoes to engage the shaft surface. With the connection means 44 thus aligned and mounted on the shaft, the sharpening unit 55 is slipped over the end of the shaft and pressed downwardly onto the connection means, over the shoulders: 56 thereof, and onto the frictional sleeves 54 carried by the offset portions 53 of the spring clips 45. In carrying this out, the clips 45 are pressed inwardly toward the shaft so that the shoes 47 are caused to grip the shaft tightly, thus enabling the shaft to drive the connection means 44 and sharpening unit 55 in rotation, since the latter are then frictionally coupled to the shaft. When it is desired to remove the sharpening unit from the coupling means 44, the end portions 46 of the spring clips 45 are pressed further inwardly toward the shaft so that the inner rims 58 and S9 of the housings 60 and 61 may clear the shoulders 56 of the spring clips 45 when the sharpening unit is removed, axially. An outstanding advantage of this form of connection means 44 consists in the ability of the spring clips 45 to be pressed inwardly toward the shaft 27 to a relatively great extent by the sharpening unit 55, and held in that position, giving rise to a good deal of radial pressure exerted on the shaft 27 by the shoes 47, and thereby increasing the frictional engagement therebetween, which is essential to efiicient coupling between the shaft and the connection means 44. By the same token, the frictional coupling or engagement between the rubber sleeves 54 and the sharpening unit rims S8 and 59 is also proportional to the pressural engagement therebetween caused by depressing the clips 45 inwardly.

The sharpening unit 63 illustrated in Fig. 6 has mounted thereon a finger 64 which depends downwardly from housing 65 to engage the blades 66 of a beater. This construction forms a positive driving connection between the sharpening unit 63 and the rotating beater so that the sharpening unit cannot slip during a knife sharpening operation. In Fig. 7, the finger 67 depends downwardly from the tapered rubber plug 68 to form a positive driving connection between the blades 66 and the plug. In this construction, the sharpening unit 63 may slip, rotatively on the rubber plug 68 during a knife sharpening operation; however, the plug 68 will be firmly coupled to the beater blades 66. The plug will consequently serve mainly as a mounting means and alignment means for the sharpening unit 63, and will keep the sharpening unit from slipping oi the plug, axially.

Referring to Fig. 8, the embodiment of the sharpening unit 69 illustrated includes an upper housing member 70 and a lower housing member 71, both comprising thin stamped members or molded plastic members. Upper housing member includes an annular portion 72 tapered outwardly and upwardly, and a flat annular portion 73 which is fastened to a similar annular portion 74 of lower housing member 71 as by spotwelds or by means of resinous adhesives. Housing member 71 is provided with an annular portion 75 which tapers radially outwardly and downwardly and which is radially coextensive with tapered portion 72 of member 78, forming therewith an annular V-shaped groove 76.

The flat surfaces of tapered portions 72 and 75 which face groove 76 are coated with thin layers of an abrasive such as a mixture of aluminum oxide, clay powder, and an aqueous solution of silicate of soda in the proper proportions and under the proper pressure to cause the abrasive mixture to adhere to the surfaces when baked at moderately high temperatures. The tapered surfaces are coated with the abrasive and baked before the housing members 70 and 71 are fastened together, so that when theyaare finally assembled, a parting line 77 will exist between the layer of abrasive 78 on tapered portion 72 and the layer of abrasive 79 on tapered portion 75, at the apex of the V-groove 76. The parting line 77 provides a very thin slot adapted to receive the feather edge of the blade during a knife sharpening operation, so that destruction of the sharpened blade edge may be prevented.

Lower housing member 71 also includes an annular dished portion 80 forming the radially inward continuation of flat portion 74, and a tapered wall portion 81 which is joined to dished portion 80 and tapers radially inwardly in an upward or axial direction. Wall portion 81 has the shape of the frustrum of a cone, and partially encloses an aperture or space'82 adapted to receive a resilient mounting member such as the tapered plug 26 described in connection with Fig. 1. Aperture 82 is sufliciently wide to permit the sharpening unit to be slipped over the collar 36 on shaft 83. Plug 26 forms a means for frictionally coupling the sharpening unit 69 to the rotatable shaft 83, which projects downwardly from the head 84 of an appliance such as an electric mixer. The function and operation of the plug 26 in forming the mounting means and driving connection means for the sharpening unit 69 on shaft 83 is the same as was described previously.

It is pointed out that the plug 26 forms a very stable mounting means for the sharpening unit 69, and the area. of the plug in contact with the walled portion 81 of the sharpening unit 69' is large enough sosthat the sharpening unit will not slip on the plug under normal torque loads encountered in a sharpening operation. Furthermore, the resilience of the plug permits the sharpening unit to be pressed into firm engagement therewith so as to keep the sharpening unit from slipping olf the plug in an axial direction, and at the same time to shrink the plug into frictional engagement with the driving shaft 83.

I claim:

1. The combination comprising a home electric mixer beater having blades connected to a stern, a deformable body centrally mounted on said stem, said body having a side surface and a central aperture extending between opposite ends of the body, there being a slot extending between said opposite ends and interconnecting said aperture with said side surface, and an annular sharpener unit encircling said beater stem and mounted on said body, said unit having an inner surface engaging said side surface and carrying annular abrasive means spaced radially outwardly from said opening.

2. The invention as defined in claim 1 including coupling means connected to said body and engageable by said heater blades.

3. The invention as defined in claim 2 in which said coupling means comprises a leg connected to said body and extending between said beater blades.

4. A cutlery sharpener assembly attachable to a home electric mixer beater having blades connected to a stem, said assembly comprising a frustro-conical body having opposite ends and a side surface and containing a central cylindrical aperture communicating longitudinally between said ends for receiving said stem, said body containing a slot communicating longitudinally between said ends and laterally between said aperture and said side surface and sized for laterally passing the stem therethrough into said aperture when said body is mounted on the heater, and an annular sharpener unit removably mounted on said body and containing a central opening adapting the unit to be freely slipped longitudinally over the beater stem into mounted position on said body, said unit extending around said body and having an inner surface engaging the side surface of the body, and said unit carrying an annular surface layer of fine-grained abrasive material spaced radially outwardly from said opening for sharpening cutlery presented to said layer upon rotation of said assembly by said heater.

5. The invention as defined in claim 4 in which the minimum outer diameter of said body is greater than twice the diameter of said aperture.

6. The invention as defined in claim 4 including a leg affixed to said body and projecting longitudinally from and for a substantial distance beyond the larger end thereof for intercoupling between said blades to connect the body in rotatable engagement with said beater.

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